1. Field of the Invention
The present invention relates to a security system and method for use in a distributed processing system. More specifically, the invention relates to a security system and method for checking passwords for validity at the time of access to nodes of more than one hierarchical levels for passthrough of access request over nodes.
2. Description of the Related Art
A security system used in a conventional network system of one-hierarchical structure is arranged as shown in FIG. 1. For example, in the case of a system wherein operator passwords are used for security, when an operator of a work station (WS) 01 logs on a CPU 02 at node 1, the password of the operator is checked for validity by an operating system (OS) of CPU 02 at node 1. The logon is a procedure for user access to a system involving identification, access control, and exchange of network information between user and system.
Such a validity checking system can realize security in one-hierarchical structure of FIG. 1.
However, a network system of two-hierarchical structure shown in FIG. 2 has a problem of no provision for security protection in the case of access over two hierarchical levels wherein the WS operator logs on CPU 02 at node 1 and moreover accesses CPU 03 at node 2 via a passthrough device in CPU 01 at node 1. That is, work station (WS) 01 thinks of itself as accessing node 1 even in the case where it actually accesses node 2. Therefore, if the password in access request data to node 1 is identified as a password stored in node 1, it is possible to gain access to node 1. In this case, however, if node 1 has not an application program specified by WS 01, node 1 would send the access request data to node 2. This means that WS 01 can access node 2 only by use of a password for access to node 1. It is theoretically possible to install a checking system in node 2 (host node). In practice, this is not practical because load on the host node increases. That is, the problem with the conventional distributed processing system is the absence of reliability of security because access request data is transferred to the next node by a passthrough device when a requested application program is not found in a node first accessed.